Method of setting-up and controlling synchronization within a modem
US6577650B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 30, 1999 |
| Grant date | Jun 10, 2003 |
| Priority date | — |
| Expiry date | Jul 30, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2662
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
To facilitate acquisition of lock in a multiple sub-channel carrier scheme, a plurality of time-continuous pilots (102) on known sub-channels are made available to an addressed unit across the frequency spectrum. The addressed unit is then able to select one of these pilots for training purposes and specifically for frequency and phase acquisition (106). The selection is based, typically, on the pilot with either the best signal to noise ratio or the first pilot to satisfy the minimum quality requirements for effective training. Discontinuous carriers, of which there can be several, are then used to identify a symbol boundary at the addressed unit. Once acquisition has been established, the pilots can, if desired, be released to carry low-bit rate traffic, although it is preferable to retain pilot tones for use within the system. Selection of the pilot from one of a number of alternative sub-channels distributed through the spectrum therefore ensures accurate synchronisation irrespective of whether portions of the spectrum are generally noisy and unclean.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.